Production of olefins



June 1957 M. J. P. BOGART' 2,796,951

PRODUCTION OF OLEFINS Filed Nov. 22, 1955 2 Sheets-Sheet 1 glg ILII IIILIIII lIlIJIlII lllll INVENTOR MIZCEL .1 E 5064/??- United States 2,796,951 Patented June 25, 1357 great and proceed into such a range that theoperation is considered hazardous. v

It is a principal object of my invention to provide an improved separation unit which permits'effectiveseparation and simultaneous production of high purity acetylene 2 7% 951 and ethylene in desired ratios With no substantial increase I in cost of operation or through excessive "duplication of PRODUCTIONCF OLEFRNS facilities such as absorbers, strippers, heat exchangers,

. etc. as'wou'ld result from conventional practice of separat- Mrl.P.B rtlV' ronk KY. ss-nrtoThe i ffi z ggg g g? ga 3?? i mg mg and purifying the acetylene and ethylene :by indlvrdual- Delaware ly difie'rent process routes.

Further objects and advantages of my invention will Applicafioll November 1955, Stlfifii Trio-543,332 10 appear from the following description thereof taken in a conjunction with 'the attached drawings in which:

2 16 Claims 115) Figure 1 1s a schematic process flow diagram forthe production and recovery of high purity ethylene and I acetylene; and This invention relates to the simultaneous recovery of Figure 21s a modified form of the process illustrated in olefins, particularly acetylene and ethylene from a'hydro- Figure 1. carbon gas mixture and'further relates'to the eflicientzsepa- In a conventional hydrocarbon cracking process in ration of these specific olefins from other close boiling which a selected hydrocarbon feed is introduced into a constituents of the gaseous mixture. high temperature'furnace or other pyrolysis gas generator, As pointed out in my copending application, Serial a cracked "gas is obtained having a composition which Number 428,489, filed May 10, 1954, now abandoned, may vary considerably depending upon the conditions at and entitled, Acetylene Production, the high temperawhich the cracking is carried out and the nature of the ture cracking of hydrocarbons either of the normally feed used. liquid or normally gaseous type in a regenerative furnace Table '1, below, gives analyses :of typical cracked gases or alternative methods for hydrocarbon pyrolysis results 25 obtained by the pyrolysis of such light hydrocarbons as in a gaseous mixture which contains, in addition to'the ethane and propane. The high-temperature regenerative desired olefins, a plurality of compounds whoseseparation cracking was carried out at substantially /2 atmosphere is both diificult and expensive. Furthermore, it is well a'bsolute total pressure, With steam dilution, :and tcmperaknown that the simultaneous recovery of ethylene and tures ranging frornlSQO" to 2300 F. The conventional acetylene is particularly diflicult because --of .thehazards cra'cking'was carried out in a tubular furnaceat slightly of operating under temperatures and pressures which above atmospheric pressure, minor quantities of dilution might otherwise be used 'for'efiective gas separation. steam, and temperatures ranging from 1470 to 1550 F.

TABLE I (Compositions in mol. percent) Charge Stock Ethane Propane Type of Cracking Tubular Regenerative Tubular Regenerative Temperature, FF.-- 1, 550 2,145 2, 205 1, 470 1,785 2,035 2,100 Pressure, p. s. 1. a- 23 7 7 17 10 8 '8 Case A B O D E F G Component:v

Hydrogen 57.5 57.2 13.1 30.3 33.0 48.6 Nitro en.-- 2.5 5.0 5.4 2.8 1.7 Carbon monoxi 6. 4 8. 4 1. 2 2. 6 6. 5 Carbon dioxide" 15 3. 9 0. 9 0.8 1.1 Methane"--- 9.3 9.8 29 4 23.2 21.7 17.5 Acetylene..- 14.7 12.9 0 2 6.2 11.9. 14.4 Ethylene-. 6.7 1.9 25 3 24.7 18.2 8.3 thane 0.3 0.2 7 2 1.0 0.0 0.2 Methylacetylene 0. 2 0. 2 0. 7 0. 7 0. 6 Propane and propylene... 1. 0 0. 2 0. 1 21. 9 4. 2 1. 6 0. 2 -Diacetylene 0.1 0.1 0.1 0.1 0.2 Butane andbutenes. 0.4 1.4 0.2. 0.1 Heavier(ind.ethyl, v yl and divinyl acetylene). 0.9 0.6 0.3 1. 5 1.3 0.9 0.7

Total 100.0 100.0 100.0 100.0 100.0 100.0 100.0 Acetylene/Ethylene Ratio 1/65 2 7 1/125 1/4 2/3 2 A comparison of the cracked gas compositionsgiven in Table I indicates a wide range in the ratio of quantities acetylene.

a gas stream on removal from the pyrolysis unit is generally passed through quench apparatus to remove tarry materials and other undesirable components which have a tendency to foul processing equipment and generally make the recovery of acetylene and ethylene more difficult. Following the quench, the gas mixture is introduced to my recovery system.

Referring to Figure 1,.a gaseous hydrocarbon mixture to be cracked is introduced into pyrolysis units 10 and 11 through lines 12 and 13 respectively. These high temperature cracking furnaces or other units for producing pyrolysis gas may be operated if desired so that the cracked gas mixture issuing from unit 10 contains a predominant quantity of acetylene relative to ethylene and the cracked gas mixture issuing from unit 11 contains a moval of the diacetylene by the solvent, absorber 27 is operated essentially at the compressor discharge pressure predominant quantity of ethylene relative to acetylene.

The relative'volumes of gas fed to these units and their operating temperatures and pressures determine the eventual relative quantity of high purity acetylene and ethylene products. in lines 14 and 15, respectively, are water quenched at 16 and 17, respectively, with Water for quenching provided through line 18. The quenching water, including tarry materials, is removed through lines 19 and 20.

To provide the predominance of acetylene in the prodnet gas of unit 10, it has been found in a regenerative furnace type of pyrolysis unit that an absolute pressure of approximately /2 atmosphere and a temperature range of between 1785 and 2265 F. are required; while to economically provide a predominance of ethylene relative to acetylene in unit 11, an absolute pressure of not below 1 atmosphere and a temperature range of from 1470 to 1550 F. are required. A vacuum pump 21 is provided in line 14 to boost the pressure of the cracked gas in such line to near atmospheric pressure, where it equals the pressure of the cracked gas in line 15. T hereafter, both cracked gas mixtures are introduced into a gas holder 22 and subsequently pass through line 23 to compressor 24. The combined cracked gases containing both acetylene and ethylene are raised to about 100-300 p. s. i. g. in compressor 24. The limitation of pressure .applied to the cracked gases by the compressor is a func- The gases issuing from units 10 and 11 20 tion of the acetylene content of the gas, where the hazards .of handling this reactive component dictates the limit in maximum partial pressure of acetylene to about 1.0

to 2.5 atmosphere absolute. This is in contrast to straight ethylene operations wherein pressures of 500-750 p. s'. i. 'g;

might be used in the absence of substantial quantities of The compressed gas in line 25 indirect heat exchange with water in cooler 26 to atem- 'perature above the hydrate formation point, with allow 1 ance made for the removal of any condensed water. j The j; cooled cracked gas in line 25 is then introduced to ab is cooled by direct or T of 100 to 300 p. s. i. g. While certain economies may be obtained by refrigerating the solvent input and the feed gas, this absorber is normally operated around 100 F.

The top of absorber 27 may be equipped with a water wash section 27c to prevent the loss of solvent overhead, clean Wash water being introduced through line 30. The water scrubber efilueut 31 and tower bottoms 32 are combined and sent to a flash separator 33 operating at near atmospheric pressure, where the combination of dilution and reduction in pressure releases most of the absorbed gas, including diacetylene, which may then be conveniently disposed of by recycling in line 34 to furnace 10. Such water-washing operations, however have the disadvantage of nullifying any dehydrating action of the solvent. In such cases I prefer to recover any solvent carried out of the top of the absorber by refrigerating the absorber. 01f gas, and removing condensed solvent therefrom for return to the absorption system.

The overhead gas leaving the preabsorber in line 35 contains most of the acetylene and ethylene and substantially all other gaseous components of the cracked gas which are less soluble than diacetylene. The 'gases of line 35 are cooled in exchanger36 and sent to the main absorber 37 wherein the C2 hydrocarbons and heavier components are absorbed in a refrigerated lean oil stream introduced through line 38. For this lean oil I prefer a light hydrocarbon in the propane-gasoline range. The lean oil stream entering absorber 37 through line 38 is circulated within the system as described hereinafter. The charge stock to the plant in line 39 may be used as supplementary sponge oil if desired and is then introduced to the main absorber through line 40 and a suitablerefrigerated heat exchanger 41. Charge stocks too volatile in character to be introduced to the system by line 39 are fed directly to the furnaces by line 39a. The inefiiciency of absorption of C2 hydrocarbons at 100-300 p. s. i. g. (as against normal practice in ethylene plants of 500 p. s. i. g. or higher) is counteracted by the intro duction of the absorption oils to absorber 37 in lines 38 and 40 at temperatures below F. Thus energy previously required to compress the absorber feed gas upto 500 p. s. i. g. is transferred to refrigerant compressorscooperating with refrigerated chillers 41 and 42 to obtain the same relative overall efficiency. The main absorber is provided with suitable contact devices in the absorption and stripping sections 37a and 37b, respectively. Stripping gas is provided by reboiler 43, in line 44, heated by any desirable medium, such as steam or hot lean oil, and serves as final removal of components less soluble than acetylene and ethylene. Gases lighter than acetylene leave tower 37 in line 45.

The main absorber bottoms comprising acetylene, ethylene, and heavier hydrocarbons from the furnace effluent, dissolved in lean oil, are removed through line top of the absorption section 27a. The solvent used such as dimethylformamide, is highly selective for higher homologs of acetylene and may also serve to remove remaining water and heavy hydrocarbons in the feed gas.

The quantity of acetylene absorbed simultaneously with the diacetylene is of the order of a few percent of that in the gas fed to the absorber by line 25. This potential loss of valuable product may be minimized, if desired, by the addition of stripping section 271) to absorber 27 and introduction of a relatively small quantity of stripping gas at the bottom of the stripping section by line 29. This stripping gas is preferably a recycled quantity of the nearly acetylene-free residual gas produced in the system. Both the absorption and stripping sections of absorber 27, as Well as subsequent towers, may be provided with packing, bubble-cap or perforated trays,.or

46 and are sent by pump 46a to stripping tower 47. This distillation tower is provided with a stripping section 47a, reboiler 48 in line 49 and a rectifying section 47b which is charged with reflux comprising substantially a mixture of nearly pure acetylene and ethylene in admixture or nearly pure ethylene, as will hereinafter be de- :hydrpcarbon cut overhead which is partially condensed scribed. The stripping tower 47 operates to give a C2 in overhead condenser 50 to provide reflux for the tower in line 55a.

The stripper bottoms in line 51 split at valve 52 into a firstportion which becomes the main absorber lean oil stream 38 and a second portion in line 53 which passes through a vaporizer 54 .and line 39a to provide the furnace charge in lines 12 and 13 when using the charge stock as sponge oil. Otherwise, the entire bottoms in line 51 are returned to the top of main absorber except for a small quantity thatmay .be redistilled :the plant.

g or sent tothe cracking furnaces for prevention ofbuildupof heavy components.

As heretofore mentioned, the overhead from stripper '47 willbe predominantly ethylene and acetylene, contaminated with any ethane and carbon dioxide in the cracked gas feed, and containing traces of methane and C3+ hydrocarbons. This overhead mixture in line '55, after passage through overhead partial condenser 50'is passed to-an acetylene absorption tower 56 where a sepa ration'is made between ethylene and acetylene by absorption of the acetylene is a selective solvent introduced by' line '57. Thesolventemployed is generally the same as that used in absorber '27, such as dimethylformamide.

Tower 56 functions as a fractionating absorber and utilizes astripping section 56a, which is supplied with suitable reboil heat by reboiler 58 in line 59. It is thus possible to make a sharp separation between the ethylene,

acetylene content which may then be passed through line 64 to'cooler'65 to condenseout any vaporized solvent an'd become the relatively pure acetylene product from If desired, heat may be introduced to the flash tank 63 by reboiler 66 in line 67. -The*solvent 'is removed through line 68 and passed through cooler 69. This cooled solvent is returned as the desired solvent of line 28 for introduction to the diacetylene preabsorber 27. A portion of the solvent of line "28*passes through line 57 to a refrigerated chiller 70 wherein it is cooled to below 60 F. and then introducedto absorber 56.

The wet solvent removed from the flash separator 53 which is a conventional distillation tower. Column 72 is supplied with reboil heat by reboiler 73 in line v74. A water cooled condenser 75 is provided in overhead line 76 of tower 72 for condensing water as an= overhead product which leaves the system in line 77. portion of the overhead condensate is returned as reflux through line 78. Non-volatile impurities and heavy-ends are eliminated from the solvent in line 71 in feed vaporizer 79. The bottoms passing from column 72 in line .80.

through line 71 is redistilled in fractionating column 72,"

-and-157.

. B. likewise contains a mixture of ethylene and acetylene simi1ar to that in line 55 of-Figure '1. However, such stream is forwarded'directly to fractionating absorber 156 without-having any portion condensed and returned ethylene and. acetylene in line 155 is again accomplished in tower 156 "by selective absorption of the acetylene in solvent, which is removed as bottoms stream'l6'1. The

overhead stream 160 comprising" substantially purethylcue from tower 156 is divided at valve 190whereby a portion of suchethylene overheadis passed through line 191, compressor-192 and refrigerated condenser -=193 to fprovide awreflux of nearlypure ethylene for thestripping tower 147. The overhead gas from tower -l47 'is then the acetylene.productdiluted-by-boththe ethylene product and the ethylene recirculated as reflux and-introduced in line 191. :The fractionatingabsorption tower-156 is operated v- 'preferably under atmospheric conditions. By spassing'only ethylene as reflux to tower -147,"s'uch tower maylbe:safely operated atabout 14 atmospheres. The remainder of'the ethylene in line 160 becomes the rela- -'tively high purity ethyleneproduct ofthe modified sys- -tem. The relative quantity of ethyleire product to acety- "le'ne Iprdducts is'ilowerin this'modified? form er "my invention,.-however;economies in operation-of: stripper 147 are obtained -by' operating at (a higher'pressure "and higher temperature. In this modified system, itrmay be like- "wise desira'ble :to introduce a repurified, portion 'of solvent 'to Ethe fractionating absorber 1'56 through line 162 and -refrigerated chil1er 181.

-- and the-solvent-removedthrough-line-168, passed through cooler 169 and returned as the desired solvent in lines 128 The alternative 1 modifications of 1 my invention provide for highly efl icient separation and simultaneous produc tion of highpurity acetylene and ethylene products in any desired ratio. Table II isan illustrationof the -operating requirements or the process route depicted in' Fig."1for-apyrolysis gas of composition as given by Case E of TableI, wherein .a'ratio of acetylene to ethylene of 1:4 isproduced in the 7 regenerative cracking unit of the plant.

constitute repurified solvent which is cooled to below 7 60 F. in refrigerated exchanger 81 before being sent to the top of column 56. If necessary, a quahtityof solvent greater than that in the bottoms from tank 333 may be redistilled in column 72 by use of jumper feed line 82. The fractionating absorber 56 is operated pref erably near atmospheric pressure for reasons-:of safety and the stripper 47 is normally operated so *th'at'th'e acetylene partial pressure of the overhead gas -is main tained in a safe region.

The system as described thus far illustrates'the simul-' taneous production of pure acetylene and ethylene wherein the ratio of acetylene to ethylene in overhead stream of tower 47 is less than one-third. Operation above a one-third ratio of acetylene to ethylene at this point would involve vproducing an acetylene-ethylene overhead TABLE II Summary of toweroperating conditions -Partia1 I Pres- Tempera Net Absorp- Pressure Designation sure, ture, Feed, tion of 01H; p. s. i. g. Top, F. Moles Solvent, in O. H.,

Moles Atmospheres Diacetylene Absorber p p 7 245 100. 0 20. 0 1.03 Main Absorber (37).... 235 40 98. 5 102.0 1.01 Stripper (47) 180 40 37. 3 59.0 2:20 Acetylene Absorber p 0 -40 37. 2 144. 0 .0001 Solvent Still (72) 0 212 1 Does not include absorption solvent. 1 0r reflux.

.Operationof the unit according tothe conditions of Table II produces product streams of the purities indicated in Table III.

V Compos tion of product stream (mol. percent h o h a r t c nt c w t e. lfic n amo n a ar? lective solvent to remove substantially all of the diacetylene, passing saidgaseous mixture througha second con- J I 'tact' with a selective solvent. oij sufiicient amountto cmnpment Acetylene Ethylene absorb substantially allot theacetylene and ethylene in said mixture separating the absorbed; gas from thesolvent ggfigggf" 3g of said second contact, passingsaid separated gas through Et r 56 %?8 a third contact with a selective solvent of suflicient amount Trgce to absorb substantially all of the acetylene therefrom, v 00 100 00 10 withdrawlng as product substantially all of the pure Tm] i 0 ethylene passing through said third contact solvent, and separating as product substantially all of. the acetylene The acetylene and ethylene producbstreams may be absorbedbyrsaidthird contactsolvent A in further Pllrlfied by wen'kPown cowennfmal means g 2. A process for simultaneously recovering substanas Y callstlc Wash 1f dew-ed It linay e tially pure acetylene and pureethylene from a gaseous noted from an msptctm of Table that. acety fi mixture obtained by the high temperature cracking of 2 Iethylene pmduc-t ratios. greater than i e hydrocarbon feed, which comprises passing said gaseous 2' atmospheres maxlmum acetylene pama presslire mixture comprising acetylene, ethylene, and diacetylene gnoted m Table For lzfcetylenf to etlylene 28 through a first contact with a sufiicient amount of a segreater than the.range of to er i lective solvent to remove substantially all of the diacetyl a g g z i a S w gi lene, passing said gaseous mixture through a second conl. e e yene s ream 15 pa y re 6 o tact with a lean oil of sufficient amount to absorb substripper 147 as the hqmd reflux for that tower As an stantiall" all of the acet lene and eth lene in said mixexample. of this alternate operation, the pertinent opert y th b d t 1 -ating requirements for the unit are given in Table IV, 3 sg f 2 f e 3 mg m f final purities of the acetylene and ethylene products will an ,y tom e can 01 o secon ac be as above except that the methane, ethane and passing said separated gas through a third contact with a ,carbon dioxide contaminants will vary with their content selective solvent of suflicient amount to absorb substanin the pyrolysis gas. Table IV b l also includes h tially all of the acetylent therefrom, withdrawing as propertinent informationfor the feed stock of Case B so duct substamlany all of the P ethylene Passlflg through that a comparison may be madewith the processing rcsaid third contact solvent, and separating as product quirements for the same stock by the process route of substantially all of the acetylene absorbed by said third Fig. 1, as given in Table III. Contact solven TABLE IV Summary of tower operating conditions i Cases of Table I V B O E G Designation Pres- Temp, Pres- Temp, Pres- Temp., Pres- Temp.,

sure, Top, sure, Top, sure, Top, sure, Top, p. s. i. g. F. p.s.i.g. F. p.s.i.g. F. p.s.1. g. F.

Diacetylene Aosorber 27) s5 7. 100 110 100 245 100 95 100 Main Absorber (37)-. 85, 40 100 40 235 40 4.0 Stripper (147) 1&0 -40 1:30 40 180 -40 180 40 ;Acetylene Absorber (156) 0 -40 0 -40 0 -40 0 -40 Solvent Still (72).. 0 212 0 212 0 212 0 212 Stream Quantities, Moles Designation B o E o Gas to Absorber 37.; 100 g 100 100 Lean Oil to Absorber 37. 258 223 102 252 Reflux to Stripper 147--- 109 59 Gas to Absorber 156. 153 124 96 162 Solvent to Absorber 1 156 629 513 405 675 Acetylene Product 15.82 13. 22 6. 50 15.17 Ethylene Product 7. 55 2. 12 30. 76 12. 10

Total Product 2 Q 23. 37 15. 34 37. 26 27 27 1 Calculated as dimethylformamide.-

1 Sum of ethylene product and acetylene product.

While I have shown and described preferred forms of 65 3. The process as claimed in claim 2 wherein the third contact solvent after separation from the product acetylene is recirculated in part to provide a portion of the solvent for said third contact and in part to provide solvent for said first contact.

4. A process for simultaneously recovering substantially pure acetylene and pure ethylene from agaseous mixture obtained by the high temperature cracking of r a hydrocarbon feed, which comprises passing said gaseous mixture comprising acetylene, ethylene, and diacetylene through a first contact with a sufficient amount of a selective solvent toremove substantiallyall of-the diacetylene, passing said gaseous mi-xture through a second contact with a selective solvent of .suflicientamount to absorb substantially all ofthe acetylene and "ethylene .in said mixture, separating the "absorbed gas from the solvent of said second contact, passing-saidseparated gas through a third contact with a major portion of refrigerated selective solvent of suflicient amount to absorb substantially all:.of the acetylene therefrom and thence 'witha minor portion of relatively high purity selective .portion of selective solvent in the'third contact is refrigerated towa'ternperature of below 60 F.

:6. [he ,process as claimed in claim 4 wherein the major and minor portions of solvent including absorbed acetylene of the third contact are combined prior to separation of said acetylene from said third contact solvents.

7. A process for simultaneously recovering substantially pure acetylene and pure ethylene from a gaseous mixture obtained by the high temperature cracking of a hydrocarbon feed, which comprises passing said gaseous mixture comprising acetylene, ethylene, and diacetylene through a first contact with a sufiicient amount of a selective solvent to remove substantially all of the diacetylene, passing said gaseous mixture through a second contact with a selective solvent of suflicient amount to absorb substantially all of the acetylene and ethylene in said mixture, separating the absorbed gas from the solvent of said second contact and refluxing said separation with a portion of such separated gases, passing the remainder of said separated gas through a third contact with a selective solvent of suflicient amount to absorb substantially all of the acetylene therefrom, withdrawing as product substantially all of the pure ethylene passing through said third contact solvent, and separating as product substantially all of the acetylene absorbed by said third contact solvent.

8. A process for simultaneously recovering substantially pure acetylene and pure ethylene from a gaseous mixture obtained by the high temperature cracking of a hydrocarbon feed, which comprises passing said gaseous mixture comprising acetylene, ethylene, and diacetylene through a first contact with a suflicient amount of a selective solvent to remove substantially all of the diacetylene, passing said gaseous mixture through a second contact with a lean oil of sufficient amount to absorb substantially all of the acetylene and ethylene in said mixture, separating the absorbed gas including acetylene and ethylene from the lean oil of said second contact and refluxing said separation with a portion of such separated gases, passing the remainder of said separated gas through a third contact with a selective solvent of sufiicient amount to absorb substantially all of the acetylene therefrom, withdrawing as product substantially all of the pure ethylene passing through said third contact solvent, and separating as product substantially all of the acetylene absorbed by said third contact solvent.

9. A process for simultaneously recovering substantially pure acetylene and pure ethylene from a gaseous mixture, obtained by the high temperature cracking of a hydrocarbon feed, which comprises passing said gaseous mixture comprising acetylene, ethylene, and diacetylene through a first contact with a suflicient amount of a selective solvent to remove substantially all of the diacetylene, passing said gaseous mixture through a second contact with a selective solvent of suificient amount to absorb substantially all of the acetylene and ethylene in said mixture, separating the absorbed gas including acetylene "and ethylene from the solvent of said second contact and refiuxing said separation; with .a .portion of the rsepa rated gases, maintaining ?.a partial pressurenof acetylene in said separation of :about 1.0 to 2.-5' atmospheres abso1ute,-passing the remainder of said separated-gas 'through a third contact with --a selective solvent of sufficient amount to absorb substantially all of: the acetylene there- ,trom, withdrawing --as product substantially allot-the pure r ethylene;passing through said third contact .solvent,

and sep arating as product substantially all of the v1 acetylene absorbed bysaid-third contact-solvent.

.10. T he. process asclaimed in" claim '9 wherein the'ratio of acetylene to'ethylene products is less than Mr to /2.

11. A process for simultaneously*recoveringasubstantially pure acetylene and pure ethylene from ra gaseous mixture obtained -by the high temperature cracking of .a hydrocarbon feed, whichcomprises passing =sa'id gaseous mixture comprising acetylene, ethylene, and tdia'cetylene through'a firstcontact with 1asuflicientamount'ofa selective solvent to remove substantially all ofwthe diacetylene, passing said gaseous mixture through a second contact with a selective solvent of suflicient amount to absorb substantially all of the acetylene and ethylene in said mixture, separating the absorbed gas from the solvent of said second contact, passing said separated gas through a third contact with a selective solvent of suflicient amount to absorb substantially all of the acetylene therefrom, withdrawing as product substantially all of the pure ethylene passing through said third contact solvent, recirculating a portion of said pure ethylene as reflux to said separation of absorbed gas from said second contact solvent, and separating as product substantially all of the acetylene absorbed by said third contact solvent.

12. A process for simultaneously recovering substantially pure acetylene and pure ethylene from a gaseous mixture obtained by the high temperature cracking of a hydrocarbon feed, which comprises passing said gaseous mixture comprising acetylene, ethylene, and diacetylene through a first contact with a suflicient amount of a selective solvent to remove substantially all of the diacetylene, passing said gaseous mixture through a second contact with a lean oil of suflicient amount to absorb substantially all of the acetylene and ethylene in said mixture, separating the absorbed gas including acetylene and ethylene from the lean oil of said second contact, passing said separated gas through a third contact with a selective solvent of suflicient amount to absorb substantially all of the acetylene therefrom, withdrawing as product substantially all of the pure ethylene passing through said third contact solvent, recirculating a portion of said pure ethylene as reflux to said separation of absorbed gas from said second contact solvent, and separating as product substantially all of the acetylene absorbed by said third contact solvent.

13. A process for simultaneously recovering substantially pure acetylene and pure ethylene from a gaseous mixture obtained by the high temperature cracking of a hydrocarbon feed, which comprises passing said gaseous mixture comprising acetylene, ethylene, and diacetylene through first contact with a sufficient amount of a selective solvent to remove substantially all of the diacetylene, passing said gaseous mixture through a second contact with a selective solvent of suflicient amount to absorb substantially all of the acetylene and ethylene in said mixture, separating the absorbed gas from the solvent of said second contact, passing said separated gas through a third contact with a selective solvent of suflicient amount to absorb substantially all of the acetylene therefrom, withdrawing as product substantially all of the pure ethylene passing through said third contact solvent, recirculating a sufiicient amount of said pure ethylene as reflux to said separation of absorbed gas from said second contact solvent whereby the partial pressure of acetylene in said separation is maintained at about 1.0 to 2.5 atmospheres absolute, and separating as product substantially all of the acetylene absorbed by said third contact solvent.

14. The process as claimed in claim 13 whereinthe ratio of acetylene to ethylene is greater than Mi to A.

-15. A process for simultaneously recovering substantially pure acetylene and;pure ethylene which comprises continuously cracking'a hydrocarbon feed under conditions to produce a gaseous mixture comprising a predominance of acetylene, continuously cracking a hydrocarbon feed under conditions to produce a gaseous mixture including a predominance of ethylene, combining the gaseous mixtures, passing said combined gaseous mixture including acetylene, ethylene, and diacetylene through a first contact with a suflicient amount of a selective solvent to remove substantially all of the diacetylene, passing said combined gaseous mixture through a second contact with a selective solvent of sutficient'amount to absorb substantially allof the acetylene and ethylene in said mixture, separating the absorbed gas from the solvent of said second contact, passing said separated gas through a third contact with a selective solvent of sufficient amount to absorb substantially all of the acetylene therefrom, withdrawing as product substantially all of the "pure ethylene passing through said third contact solvent, and separating as product substantially all of the acetylene absorbed by said third contact solvent.

16. The process as claimed in claim 15 wherein said on in a furnace at an absolute pressure of at least 1 atmosphere and a temperature of between 1470" F. and 1550 F.

References Cited in the file of this patent UNITED STATES PATENTS 2,250,925 Babcock July 29, 1941 2,714,940 Milligan Aug. 9, 1955 2,726,734 Nirenberg Dec. 13, 1955 20 2,731,507 Akin Jan. 17, 1956 

1. A PROCESS FOR SIMULTANEOUSLY RECOVERING SUBSTANTIALLY PURE ACETYLENE AND PURE ETHYLENE FROM A GASEOUS MIXTURE OBTAINED BY THE HIGH TEMPERATURE CRACKING OF A HYDROCARBON FEED, WHICH COMPRISES PASSING SAID GASEOUS MIXTURE COMPRISING ACETYLENE, ETHYLENE, AND DIACETYLENE THROUGH A FIRST CONTACT WITH A SUFFICIENT AMOUNT OF A SELECTIVE SOLVENT TO REMOVE SUBSTANTIALLY ALL OF THE DIACETYLENE, PASSING SAID GASEOUS MIXTURE THROUGH A SECOND CON TACT WITH A SELECTIVE SOLVENT OF SUFFICIENT AMOUNT TO ABSORB SUBSTANTIALLY ALL OF THE ACETYLENE AND ETHYLENE IN SAID MIXTURE, SEPARATING THE ABSORBED GAS FROM THE SOLVENT OF SAID SECOND CONTACT, PASSING SAID SEPARATED GAS THROUGH A THIRD CONTACT WITH A SELECTIVE SOLVENT OF SUFFICIENT AMOUNT 